How to exit from ForEach-Object in PowerShell

Question

I have the following code   project PropertyGroup   Foreach-Object       if    GetAttribute  Condition   Trim   -eq  propertyGroupConditionName Trim               a    project RemoveChild              Write-Host    GetAttribute  Condition   quot has been removed  quot             Question  1  How do I exit from ForEach-Object  I tried using  quot break quot  and  quot continue quot   but it doesn t work  Question  2  I found that I can alter the list within a foreach loop    We can t do it like that in C     Why does PowerShell allow us to do that

User · Answer

Below is a suggested approach to Question #1 which I use if I wish to use the ForEach-Object cmdlet. It does not directly answer the question because it does not EXIT the pipeline. However, it may achieve the desired effect in Q#1. The only drawback an amateur like myself can see is when processing large pipeline iterations.

    $zStop = $false
    (97..122) | Where-Object {$zStop -eq $false} | ForEach-Object {
    $zNumeric = $_
    $zAlpha = [char]$zNumeric
    Write-Host -ForegroundColor Yellow ("{0,4} = {1}" -f ($zNumeric, $zAlpha))
    if ($zAlpha -eq "m") {$zStop = $true}
    }
    Write-Host -ForegroundColor Green "My PSVersion = 5.1.18362.145"

I hope this is of use. Happy New Year to all.

User · Answer

Answer for Question  1 - You could simply have your if statement stop being TRUE   project PropertyGroup   Foreach       if     GetAttribute  Condition   Trim   -eq  propertyGroupConditionName Trim    -and   FinishLoop             a    project RemoveChild              Write-Host    GetAttribute  Condition   has been removed             FinishLoop    true

User · Answer

Item  1  Putting a break within the foreach loop does exit the loop  but it does not stop the pipeline  It sounds like you want something like this    todo  project PropertyGroup  foreach   thing in  todo       if   thing -eq  some condition            break           Item  2  PowerShell lets you modify an array within a foreach loop over that array  but those changes do not take effect until you exit the loop  Try running the code below for an example    a 1 2 3 foreach   value in  a     Write-Host  value   Write-Host  a   I can t comment on why the authors of PowerShell allowed this  but most other scripting languages  Perl  Python and shell  allow similar constructs

User · Answer

If you insist on using ForEach-Object  then I would suggest adding a  break condition  like this    Break    False   1 2 3 4   Where-Object    Break -Eq  False     ForEach-Object         Break      -Eq 3       Write-Host  Current number is          The above code must output 1 2 3 and then skip  break before  4  Expected output   Current number is 1 Current number is 2 Current number is 3

User · Answer

You have two options to abruptly exit out of ForEach-Object pipeline in PowerShell   Apply exit logic in Where-Object first  then pass objects to Foreach-Object   or  where possible  convert Foreach-Object into a standard Foreach looping construct   Let s see examples  Following scripts exit out of Foreach-Object loop after 2nd iteration  i e  pipeline iterates only 2 times  quot   Solution-1  use Where-Object filter BEFORE Foreach-Object   boolean  exit    false  1  10   Where-Object   exit -eq  false    Foreach-Object        if    -eq 2    exit    true      OR  exit       -eq 2               OR 1  10   Where-Object     -le 2    Foreach-Object               Solution-2  Converted Foreach-Object into standard Foreach looping construct  Foreach   i in 1  10          if   i -eq 3   break         i     PowerShell should really provide a bit more straightforward way to exit or break out from within the body of a Foreach-Object pipeline  Note  return doesn t exit  it only skips specific iteration  similar to continue in most programming languages   here is an example of return  Write-Host  quot Following will only skip one iteration  actually iterates all 10 times  quot   1  10   Foreach-Object        if     -eq 3   return     skips only 3rd iteration              HTH

User · Answer

I found this question while looking for a way to have fine grained flow control to break from a specific block of code  The solution I settled on wasn t mentioned     Using labels with the break keyword  From  about break     A Break statement can include a label that lets you exit embedded   loops  A label can specify any loop keyword  such as Foreach  For  or   While  in a script    Here s a simple example   myLabel for  i   1   i -le 2   i              Write-Host  Iteration   i          break myLabel    Write-Host  After for loop     Results    Iteration  1   After for loop   And then a more complicated example that shows the results with nested labels and breaking each one    outerLabel for  outer   1   outer -le 2   outer            innerLabel for  inner   1   inner -le 2   inner              Write-Host  Outer   outer   Inner   inner           break innerLabel          break outerLabel            Write-Host  After Inner Loop     Write-Host  After Outer Loop     Both breaks commented out   Outer  1   Inner  1   Outer  1   Inner  2   After Inner Loop   Outer  2   Inner  1   Outer  2   Inner  2   After Inner Loop   After Outer Loop    break innerLabel Results   Outer  1   Inner  1   After Inner Loop   Outer  2   Inner  1   After Inner Loop   After Outer Loop    break outerLabel Results   Outer  1   Inner  1   After Outer Loop   You can also adapt it to work in other situations by wrapping blocks of code in loops that will only execute once    myLabel do       1  2                Write-Host  Iteration              break myLabel          while   false   Write-Host  After do while loop     Results    Iteration  1   After do while loop

User · Answer

Since ForEach-Object is a cmdlet  break and continue will behave differently here than with the foreach keyword  Both will stop the loop but will also terminate the entire script   break   0  3   foreach       if     -eq 2    break            echo  Never printed     OUTPUT    0   1   continue   0  3   foreach       if     -eq 2    continue            echo  Never printed     OUTPUT    0   1   So far  I have not found a  good  way to break a foreach script block without breaking the script  except  abusing  exceptions   throw   try       0  3   foreach           if     -eq 2    throw                      catch     echo  End     OUTPUT    0   1   End   The alternative  which is not always possible  would be to use the foreach keyword   foreach   foreach     in  0  3         if     -eq 2    break            echo  End     OUTPUT    0   1   End

User · Answer

There are differences between foreach and foreach-object   A very good description you can find here  MS-ScriptingGuy  For testing in PS  here you have scripts to show the difference   ForEach-Object     Omit 5  1  10   ForEach-Object   if     -eq 5   return    if     -ge 5   return    Omit from 5  Write-Host      write-host  after1      Cancels whole script at 15   after2  not printed  11  20   ForEach-Object   if     -eq 15   continue  Write-Host      write-host  after2      Cancels whole script at 25   after3  not printed  21  30   ForEach-Object   if     -eq 25   break  Write-Host      write-host  after3    foreach    Ends foreach at 5  foreach   number1 in  1  10     if   number1 -eq 5   break  Write-Host   number1    write-host  after1      Omit 15   foreach   number2 in  11  20     if   number2 -eq 15   continue  Write-Host   number2    write-host  after2      Cancels whole script at 25   after3  not printed  foreach   number3 in  21  30     if   number3 -eq 25   return  Write-Host   number3    write-host  after3

User · Answer

To stop the pipeline of which ForEach-Object is part just use the statement continue inside the script block under ForEach-Object  continue behaves differently when you use it in foreach            and in ForEach-Object       and this is why it s possible  If you want to carry on producing objects in the pipeline discarding some of the original objects  then the best way to do it is to filter out using Where-Object

[powershell] How to exit from ForEach-Object in PowerShell

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